I agree, that would be nice. However, given that Daggerfall plays specific music according to location/daytime, we would need some way of configuring when to choose which files. Maybe a structure of pre defined directories?

In this manner it would be possible to add more versions of DF music tracks, now that more people engage in remastering them.

This tutorial from LypyL should be a good start. It should be feasible to make a plugin that extends the modding system and imports new songs from loose files, somewhat like the location mod from Uncanny_Valley.

If you are interested in creating mods for Daggerfall Unity you can find the documentation here.